Thermal Energy Transfer and Properties

These flashcards cover key vocabulary terms related to thermal energy, its properties, transfer mechanisms, and effects.

Thermal energy

Kinetic and potential energy of the random microscopic motions of molecules, atoms, ions, and other particles.

Heat transfer

The transfer of thermal energy from a hotter body to a colder body.

Caloric fluid

Historical concept that heat was an invisible fluid; now understood as thermal energy.

Calorie

Traditional unit of heat defined as the amount of heat required to raise the temperature of 1 gram of water by 1°C.

Specific heat capacity

Amount of heat needed to raise the temperature of 1 kg of a material by 1°C.

Thermal expansion

The increase in volume or size of a substance due to an increase in temperature.

Adiabatic process

A thermodynamic process in which no heat is exchanged with the surroundings.

Thermal conductivity

A material's ability to conduct heat.

Phase change

A transformation from one state of matter (solid, liquid, gas) to another.

Latent heat

The heat required for a substance to change its state without changing its temperature.

Heat engine

A device that converts thermal energy into mechanical work.

Conduction

Heat transfer through direct contact between materials.

Convection

Heat transfer through the movement of fluids.

Radiation

Heat transfer through electromagnetic waves.

Free electrons

Electrons that are not bound to an atom and can move freely, contributing to thermal and electrical conductivity.

Degree Celsius (°C)

A unit of temperature where water freezes at 0°C and boils at 100°C at 1 atm.

British thermal unit (Btu)

The amount of heat needed to raise the temperature of 1 pound of water by 1°F.

Magnitudes of specific heats

Variations in specific heat depending on the substance and state of matter.

Thermal inertia

The property of a material to resist changes in temperature.

Equilibrium temperature

The temperature at which heat entering a system equals heat leaving the system.

Coefficient of linear expansion

A measure of how much a material expands per unit length for a unit change in temperature.

Coefficient of volume expansion

A measure of how much a material expands per unit volume for a unit change in temperature.

R-Value

A measure of insulation's resistance to heat flow; higher values indicate better insulating properties.

Work done on a gas

The energy transferred to a gas when it is compressed or expanded.

Thermal inertia of water

The ability of water to absorb heat without a significant temperature change.

Molar specific heat

The heat capacity per mole for a substance at constant volume or pressure.

Pressure-volume relationship

Describes how pressure and volume of a gas change during adiabatic and non-adiabatic processes.

Thermal motion

Random motion of particles in a substance associated with the object's temperature.

Energy conservation principle

Energy cannot be created or destroyed, only transformed.

Heating systems

Systems in homes that use water or air to transfer heat throughout the space.

Thermoelectric effect

Conversion of temperature differences directly into electric voltage.

Insulators

Materials that do not conduct heat well; used to prevent heat loss.

Conductors

Materials that conduct heat efficiently, allowing for quick transfer of thermal energy.

Thermodynamics

The branch of physics that deals with heat, work, and how they relate to energy and matter.

Entropy

A measure of disorder in a system; in thermodynamics, it indicates the direction of spontaneous change.

Mechanical equivalent of heat

The conversion factor that relates heat energy to mechanical work.

Ideal gas law

Equation of state relates pressure, volume, temperature, and number of moles of an ideal gas.

Monoatomic gas

A gas composed of single atoms, such as helium or argon.

Diatomic gas

A gas composed of molecules made up of two atoms, like oxygen (O2) or nitrogen (N2).

Gas laws

The laws governing the behavior of gases in terms of pressure, volume, and temperature.

Piston

A component of engines and compressors used to compress or expand gases.

Internal energy

Energy stored in a substance due to its temperature, pressure, and volume.

Thermal equilibrium

A state where two bodies in thermal contact do not exchange heat.

Thermal flow

The rate at which heat is transferred through materials.

Equilibrium state

Condition where all macroscopic properties of a system are stable.

U-value

A measure of thermal transmittance; the inverse of the R-value.

Thermal efficiency

A measure of how well an energy conversion system performs compared to the ideal maximum output.

Heat loss

The transfer of thermal energy out of a building or system.

Specific latent heat

The amount of heat required to change the state of a unit mass without changing its temperature.

Sensible heat

The heat exchanged by a thermodynamic system that results in a temperature change.

Insulation material

Materials used to reduce the rate of heat transfer.